DE102022206482A1 - Method for adapting a pressure characteristic curve of a frictional switching element of a transmission and control device - Google Patents

Abstract

Method for adapting a pressure characteristic curve (6) of a frictional switching element of a transmission of a motor vehicle, wherein a rapid filling time is adapted for a rapid filling pressure via a rapid filling time adaptation of the frictional switching element, and wherein in this case a transmission-side rapid filling time adaptation reaction to the rapid filling time adaptation is determined with the following steps: A characteristic point on the pressure characteristic curve (6) to be adapted is selected or assumed as the characteristic point to be adapted, which is then set when the switching element is activated with the quick filling pressure for a control time period for closing, which is a defined one Time span is shorter than the adapted quick fill time. To adapt the pressure in this characteristic point, the switching element is first activated to close with the quick filling pressure for a first period of time, the first period of time being shorter than the adapted quick filling time by the defined period of time. The switching element is then activated for a waiting period with a waiting pressure that is smaller than the quick filling pressure. Subsequently, the switching element is controlled with the quick filling pressure for a second period of time, which corresponds to the defined period of time, and a transmission-side adaptation reaction is determined. Then, if it is determined that the adaptation reaction corresponds to the reaction to the quick filling time adaptation, the current waiting pressure is determined as the pressure to be adapted in the characteristic point of the pressure characteristic curve to be adapted.

Description

The invention relates to a method for adapting a pressure characteristic curve of a frictional switching element of a transmission. The invention further relates to a control device for operating a transmission.

A drive train of a motor vehicle has a drive unit and a transmission connected between the drive unit and an output. The transmission converts speeds and torques and provides the traction power of the drive unit to the output. The transmission has several switching elements, which can be designed as frictional switching elements and/or as positive switching elements. A frictional switching element is in particular a clutch or brake. A positive switching element is in particular a claw. In each engaged gear of a transmission, a first number of the shifting elements of the transmission are closed and a second number of the shifting elements of the transmission are opened. To carry out a gear change, at least one previously closed shifting element is opened and at least one previously opened shifting element is closed.

The switching elements of a transmission are controlled for closing using a pressure control, with the pressure control of a switching element depending on at least one pressure characteristic curve. For example, a pressure-time characteristic curve and a pressure-displacement characteristic curve are known as the pressure characteristic curve of a frictional switching element of a transmission. The pressure-time characteristic curve defines a time course of the pressure control of a switching element and is divided into several phases, for example a quick filling phase, a filling compensation phase and further phases following the filling compensation phase. A pressure-path characteristic curve defines an adjustment path of the frictional switching element depending on the control pressure.

From the DE 100 42 146 A1 and the US 8,510,006 B2 Pressure-time characteristics of frictional switching elements of a transmission are known, as well as methods with which a quick filling time of a quick filling phase can be adapted.

WO 2022/017 554 A1 , WO 2018/014 905 A1 , DE 10 2019 100 376 A1 and also US 8,843,289 B2 disclose further details of a pressure control of frictional switching elements of a transmission.

Although it is already known to adapt the quick filling time of a frictional switching element during a rapid filling time adaptation for a rapid filling pressure and to control a frictional switching element for closing depending on this, there is a need to improve the control of a frictional switching element, namely to enable it with even higher quality . In particular, there is a need to adapt a touch point and/or a contact point of a pressure characteristic curve, in particular a pressure-travel characteristic curve, of a frictional switching element in order to carry out the closing process of a frictional switching element even more precisely and thus with even higher quality can.

Proceeding from this, the invention is based on the object of creating a novel method and control device for adapting a pressure characteristic curve of a frictional switching element of a transmission.

This object is achieved by a method for adapting a pressure characteristic of a frictional switching element of a transmission of a motor vehicle according to claim 1.

According to the invention, a characteristic point on the pressure characteristic curve to be adapted is selected or assumed as the characteristic point to be adapted, which occurs when the switching element is activated to close with the quick filling pressure for a control time period that is a defined period of time shorter than the adapted quick filling time.

According to the invention, in order to adapt the pressure in this characteristic point, the switching element is first activated for a first period of time with the rapid filling pressure to close, the first period of time being shorter than the adapted rapid filling time by the defined period of time.

The switching element is then activated for a waiting period with a waiting pressure that is smaller than the quick filling pressure.

Subsequently, the switching element is controlled for a second period of time, which corresponds to the defined period of time, with the quick filling pressure and a transmission-side adaptation reaction is determined. Then, if it is determined that the adaptation reaction corresponds to the reaction to the quick filling time adaptation, the current waiting pressure is determined as the pressure to be adapted in the characteristic point of the pressure characteristic curve to be adapted.

The method according to the invention sets an adaptation of the quick filling time over one per se known fast filling time adaptation. The quick filling time adaptation can be carried out in the manner known from the prior art.

Based on the determined quick filling time, a point on the pressure characteristic curve to be adapted is selected, which occurs when the switching element is activated with the quick filling pressure for a control time to close that is shorter by a defined period of time than the adapted quick filling time. The pressure in this characteristic point is adapted via the above method steps, namely by first controlling the switching element for the first time period with the quick filling pressure to close, the first time period being shorter by the defined time period than the adapted quick filling time, with the switching element subsequently for the waiting period is controlled with the waiting pressure, which is smaller than the quick filling pressure, the switching element subsequently being controlled with the quick filling pressure for the second period of time, which corresponds to the defined period of time, and a transmission-side adaptation reaction is determined.

Then, if it is determined that the adaptation reaction corresponds to the reaction to the quick filling time adaptation, the current waiting pressure is determined as the pressure to be adapted in the characteristic point of the pressure characteristic curve to be adapted.

If, on the other hand, it is determined that the adaptation reaction does not correspond to the reaction to the quick filling time adaptation, i.e. deviates from it by more than a defined limit value, the waiting pressure is increased by a defined increment and the above method steps are carried out again, in this way frequent repetition with an incremental increase in the waiting pressure until the adaptation response corresponds to the response to the quick fill time adaptation.

A pressure characteristic curve adapted in this way can ensure highly precise and high-quality control of frictional switching elements of a transmission.

Preferably, a touch point and/or a contact point and/or a characteristic point between the touch point and the contact point is adapted as a characteristic point on the pressure characteristic curve to be adapted. The method according to the invention is preferably used to adapt the touch point and/or the contact point and/or a point between the touch point and the contact point on the pressure characteristic curve. The touch point is the point on the pressure characteristic curve from which a frictional switching element begins to transmit torque, based on drag torque. The contact point is the point at which the frictional switching element begins to transmit torque, primarily based on friction between switching element halves of the respective frictional switching element.

The control device for operating a transmission of a motor vehicle is defined in claim 6.

• 1 ein reibschlüssiges Schaltelement mit Wellfeder in unterschiedlichen Schließpositionen;
• 2 eine Druck-Kennlinie des reibschlüssigen Schaltelements der 1;
• 3 abhängig von einer Schnellfüllzeit-Adaption ermittelte Kenngrößen des reibschlüssigen Schaltelements;
• 4 ein Diagramm zur Verdeutlichung der erfindungsgemäßen Adaption bei der Adaption eines Touch-Points und bei der Adaption eines Contact-Points der Druck-Kennlinie des reibschlüssigen Schaltelements.

Preferred further developments result from the subclaims and the following description. Exemplary embodiments of the invention are explained in more detail using the drawing, without being limited to this. This shows:

• 1 a frictional switching element with a wave spring in different closing positions;
• 2 a pressure characteristic curve of the frictional switching element 1 ;
• 3 Characteristics of the frictional switching element determined depending on a quick filling time adaptation;
• 4 a diagram to illustrate the adaptation according to the invention when adapting a touch point and when adapting a contact point of the pressure characteristic curve of the frictional switching element.

1 shows a highly schematic view of a frictional switching element 1 of a transmission of a motor vehicle, which comprises two switching element halves 2, 3. Each switching element half 2, 3 has several slats. The switching element halves 2, 3 can be displaced relative to one another depending on a pressure control 4, which acts on a piston (not shown) of the frictional switching element 1, in order to close or open the respective switching element 1. The switching element 1 of the 1 still has a wave spring 5.

In the left state the 1 If the switching element 1 is completely open, it then does not transmit any torque, and there is maximum clearance between the switching element halves 2, 3.

In the second state from the left, switching element 1 is the 1 closed up to the so-called touch point TP, whereby there is still a clearance in the touch point TP and the switching element 1 begins to transmit torque, mainly due to drag torque.

If the switching element 1 is closed further, it subsequently assumes the third state from the left 1 one in which that Switching element 1 is closed up to the contact point CP. In the contact point CP, the clearance between the switching element halves 2, 3 is completely eliminated, the frictional switching element 1 then begins to transmit torque mainly through friction between the switching element halves 2, 3.

When the switching element 1 is closed further, a wave spring 5 of the same is compressed, when the switching element 1 is in the 1 in the right state of the 1 is located, the wave spring 5 is compressed and the switching element 1 changes from an elastic state to a rigid state.

The point at which the wave spring 5 is compressed and at which the frictional switching element 1 changes from the elastic state to the rigid state is also referred to as the reaction point RP.

2 shows the switching element 1 1 a pressure characteristic curve, namely a pressure-path characteristic curve 6, which shows a dependency between the control pressure p and an adjustment path s of the piston of the frictional switching element 1. A characteristic curve area 6a visualizes the switching path s of the switching element 1, starting from an opened clutch to the touch point TP. The characteristic curve area 6b visualizes the pressure-path dependency between the touch point TP and the contact point CP. The characteristic curve area 6c visualizes the pressure-path dependency between the contact point CP and the reaction point RP. The characteristic curve range 6d visualizes the adjustment path s of the frictional switching element 1 as a function of the pressure control p for the rigid state of the switching element 1.

The invention is now about based on the pressure-displacement characteristic curve 2 to adapt the touch point TP and/or the contact point CP and/or any characteristic point on the characteristic curve range 6b between the touch point TP and the contact point CP.

For this adaptation, the result of a quick filling time adaptation of the frictional switching element 1 is used, via which a quick filling time of the frictional switching element is adapted for a quick filling pressure. Details of such a quick filling time adaptation are familiar to the expert addressed here, for example from DE 100 42 146 A1 as well as from the US 8,510,006 B2 . The quick filling time of the frictional switching element is adapted via a quick filling time adaptation, with a quick filling pressure in the drive train being recognized in particular as a reaction to the quick filling time adaptation. In the case of a quick filling time adaptation, a characteristic point is determined on the pressure-displacement characteristic curve 6, which corresponds to 2 lies on the characteristic curve section 6c, i.e. between the contact point CP and the reaction point RP. The characteristic point determined during the quick filling time adaptation is, for example, characteristic point 7 2 .

The curve 8 of the 3 , in which the control pressure p is plotted over time t, shows the result of a quick filling time adaptation. A switching element 1 is controlled with a quick filling pressure pSF until the quick filling time adaptation reaction is detected, the time period tSF between the start of a quick filling phase and the recognition of the quick filling time adaptation reaction corresponding to the adapted quick filling time tSF.

On the transmission control side, a first time period ΔtCP is stored for the contact point CP and a second defined time period ΔtTP is stored for the touch point TP, by which the adapted quick filling time tSF is to be reduced in order to depend on a stored pressure-displacement characteristic curve to be adapted according to the invention 6 to close the frictional switching element 1 up to the contact point CP or up to the touch point TP.

The curve 9 thus visualizes a control of a frictional switching element 1 with the quick filling pressure pSF with a control time period tSF-ΔtCP, which is shorter than the adapted quick filling time tSF by the first defined time period ΔtCP. The course of the curve 10 3 visualizes the control of the frictional switching element 1 with the control time period tSF-ΔtTP, which is shorter by the second defined time period ΔtTP than the adapted quick filling time tSF.

In order to now adapt the touch point TP of the pressure-displacement characteristic curve 6 depending on the adapted quick filling time tSF, which was adapted in a known manner, as in 4 with the curve 11 shown, proceeded.

To adapt the pressure pTP in the touch point TP, in the adaptation according to the invention, the frictional switching element 1 is controlled to close for a first time period tSF-ΔtTP with the quick filling pressure pSF, this first time period being shorter by the defined first time period ΔtTP than the adapted quick filling time tSF is.

Subsequently, the switching element is activated for a waiting time ΔtW with a waiting pressure pW that is smaller than the pressure pTP to be adapted in the touch point TP.

Following this waiting time ΔtW, the frictional switching element is again controlled to close with the quick filling pressure pSF for a second period of time, which corresponds to the defined period of time ΔtTP, and the transmission-side adaptation reaction is determined at the end of this second period of time ΔtTP.

If it is determined that this adaptation reaction corresponds to the reaction of the quick filling time adaptation, the current waiting pressure pW is determined as the pressure to be adapted in the touch point TP of the pressure characteristic curve 6 to be adapted.

If, on the other hand, it is determined that the adaptation reaction deviates from the reaction to the quick filling time adaptation by more than one limit value, i.e. does not correspond to it, the waiting pressure pW is increased by a defined increment and the above steps are carried out again, with an incremental increase in the waiting pressure until it is determined that the adaptation reaction of the method according to the invention corresponds to the reaction to the quick filling time adaptation.

The curve 12 shows the procedure for adapting the pressure for the contact point CP of the pressure characteristic curve 6, for which purpose the frictional switching element 1 is first controlled to close for a first period of time tSF-ΔtCP with the quick filling pressure pSF, this first period of time is shorter than the adapted quick filling time tSF by the defined time period ΔtCP. Subsequently, the switching element 1 is controlled for the waiting time ΔtW with a waiting pressure PW which is smaller than the pressure pCP to be adapted of the contact point CP to be adapted. Subsequently, the switching element is again controlled with the rapid filling pressure pSF for a defined second period of time, which corresponds to the defined period of time ΔtCP of the contact point CP, and the adaptation reaction on the transmission side is again determined. If this adaptation reaction matches the reaction to the quick filling time adaptation, the current waiting pressure is determined as the pressure pCP to be adapted for the contact point CP. However, if this is not the case, the waiting pressure pW is increased by an increment and the above method is carried out again, with an incremental increase in the waiting pressure until the adaptation reaction corresponds to the reaction to the quick filling time adaptation.

Using the method described above, each characteristic point on the characteristic curve area 6b of the pressure characteristic curve 6 can be adapted between the touch point TP and the contact point CP.

A frictional switching element, in particular between the touch point TP and the contact point CP, can be controlled very precisely with high quality using a pressure characteristic curve 6 adapted using the method according to the invention.

The invention further relates to a control device which is set up to automatically carry out the method described above. This control unit is in particular an electronic transmission control unit of a transmission of a motor vehicle. Such an electronic transmission control unit has hardware-side means and software-side means. The hardware-side means include, in particular, data interfaces in order to exchange data with the assemblies involved in carrying out the method according to the invention, for example with hydraulic valves for pressurizing the switching element 1. The hardware-side means also include a memory for data storage and a processor for data processing. The software-side means include program blocks that are implemented in the control device for automatically executing the method according to the invention.

Reference symbols

1

Switching element

2

switching element half

3

switching element half

4

Pressure control

5

Wave spring

6

Pressure characteristic curve

6a

Characteristic range

6b

Characteristic range

6c

Characteristic range

6d

Characteristic range

7

characteristic point

8th

Curve course

9

Curve course

10

Curve course

11

Curve course

12

Curve course

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 10042146 A1 [0004, 0029]
• US 8510006 B2 [0004, 0029]
• WO 2022/017554 A1 [0005]
• WO 2018/014905 A1 [0005]
• DE 102019100376 A1 [0005]
• US 8843289 B2 [0005]

Claims (6)

Method for adapting a pressure characteristic curve of a frictional switching element (1) of a transmission of a motor vehicle, wherein a quick filling time of the frictional switching element (1) is adapted for a quick filling pressure via a quick filling time adaptation of the frictional switching element (1), in which case a transmission-side quick filling time adaptation reaction to the quick filling time adaptation is determined, marked the following steps: a) a characteristic point on the pressure characteristic curve (6) to be adapted is selected or assumed as the characteristic point to be adapted, which is set when the switching element (1) is activated with the quick filling pressure for a control time period that is shorter than a defined period of time than the adapted quick fill time, b) to adapt the pressure in this characteristic point, the switching element (1) is first activated to close with the quick filling pressure for a first period of time, the first period of time being shorter than the adapted quick filling time by the defined period of time, c) the switching element (1) is subsequently activated for a waiting period with a waiting pressure that is smaller than the quick filling pressure, d) the switching element (1) is subsequently controlled with the quick filling pressure for a second period of time, which corresponds to the defined period of time, and a transmission-side adaptation reaction is determined, e) if it is determined that the adaptation reaction corresponds to the reaction to the quick filling time adaptation, the current waiting pressure is determined as the pressure to be adapted in the characteristic point of the pressure characteristic curve to be adapted. Procedure according to Claim 1 , characterized in that if it is determined that the adaptation reaction does not correspond to the reaction to the quick filling time adaptation, the waiting pressure is increased by a defined increment and steps b) to e) are carried out again. Procedure according to Claim 1 or 2 , characterized in that a touch point is adapted as a characteristic point on the pressure characteristic curve to be adapted. Procedure according to one of the Claims 1 until 3 , characterized in that a contact point is adapted as a characteristic point on the pressure characteristic curve to be adapted. Procedure according to one of the Claims 1 until 4 , characterized in that a characteristic point between a touch point and a contact point is adapted as a characteristic point on the pressure characteristic curve to be adapted. Control device for operating a transmission of a motor vehicle, characterized in that the control device is set up to carry out the method according to one of the Claims 1 until 5 to execute automatically.

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